Sign



July 10, 1951 R. w. MALLARY 2,560,117

SIGN

Filed Jan. 31, 1947 2 Sheets-Sheet 1 5i i I I: M f

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INVENTOR ROBERT W. MALLARY ATTORNEY July 10, 1951 R. w. MALLARY SIGNFiled Jan. :51, 1947 2 Sheets-Sheet 2 ww g I l I r 7/ ///H/ INVENTORROBERT W. MALLARY ATTORNEY Patented July 10, 1951 UNITED STATES PATENTOFFICE SIGN Robert W. Mallary, Los Angeles, Calif.

Application January 31, 1947, Serial No. 725,497

4 Claims.

This invention relates generally to illuminated signs, and relates moreparticularly to signs of the edge-lighted type utilizing transparent andtranslucent materials such as plastics.

It is an object of the invention to provide devices of this characterwherein great diversity and control of optical effects may be produced.

Another object of the invention is to provide a panel of suitablecharacteristics in which sign characters, such as letters, numerals andthe like, may be variously embedded to produce various effects. Forexample, the sign characters may be wholly embedded in the panel. Ihus,by removing the sign characters or decorative features from contact withthe air, and embedding them within a substantially transparent block orpanel, the basic means is provided for the control and exploitation ofdifferences in color, degree of translucency and refractiveindex, forthe purpose of developing a great many different optical eifects. Theadvantages of embedding the sign characters and figures results in ahigh degree of control of the optical effects desired, particularly asregards those effects resulting from the combination of materials ofdifferent as well as identical indices of refraction.

Further advantages reside in the economical utilization of the lightentering the panel from the edge resulting from the property of totalinternal reflection, a more even illumination of the sign characters,also owing to the effects of the total internal reflection of light, andthe enhanced effect on the appearance of the sign characters when seenthrough a refractory transparent medium. Other eifects'may also besecured by but partially embedding the sign characters or figures in thepanel.

Still another object of the invention isthe provision of a device ofthis character wherein addiitional effects may be produced by rougheningcertain surfaces of either the panel or the sign characters, or both.

A further object of the invention is to provide a device of thischaracter wherein still additional effects may be produced by specialtreatment of certain surfaces such as the rear surface of the panel, soas to provide a back drop for the sign characters and the like.

A, still further object of the invention is to provide a device of thischaracter wherein an attractive three-dimensional spacious effect isproduced.

One of the advantages Of embedding the sign characters in the panel isthat it isolates such characters from dirt and the like, so that theSign is easily cleaned and polished, and may be 2 rebufied should thatbe necessary after a period of use.

In many edge-lighted signs now in use the illumination is intense overthe lower portion of the sign characters but is weak over the upperportion, or vice versa, and it is therefore another object of theinvention to provide a device of this character wherein there isrelatively even illumination of the sign characters. One factor insecuring such even illumination is the characteristics of the signcharacters themselves which readily transmit light to all parts thereof.Another feature of the invention which aids in effecting evenillumination of the sign characters is the use of a plurality of lightsources. For example, the panel is illuminated from a plurality ofsides, as from the top and bottom, and the panel is provided withrearwardly extending portions having the top and bottom edges curved soas to illuminate the sign characters evenly.

Still another object of the invention is to provide a device of thischaracter wherein the illuminated parts of the device differ opticallyfrom each other in some respect, so as to afford contrast and variety.

A further object of the invention is to provide a device of thischaracter wherein the sign characters are fully visible throughout awide range of viewing positions.

A still further object of the invention is to provide a device of thischaracter wherein sign characters and the like, havingvarious differentoptical characteristics may be employed within the same sign.

A still further object of the invention is to provide a device of thischaracter wherein sign characters may be so disposed that some of saidcharacters are in front of others, while all said characters are visiblein their entirety.

A still further object of the invention is to provide a device of thischaracter, wherein actual objects, or facsimile objects, may be embeddedin the panel, such as, for example, bottles, etc.

Further objects and advantages of the invention will be brought out inthe following part of the specification.

Referring to the drawings, which are for illustrative purposes only,

Fig. 1 is a perspective view of a sign embodying the present invention;

Fig. 2 is a sectional view taken on line 22 of Fig. 1;

Fig, 3 is a fragmentary sectional View showing an alternativearrangement of the panel and sign characters;

Fig. 4 is a perspective View of a sign embodying an actual objectembedded in the panel; and

Fig. 5 is a perspective view of an alternative arrangement of theinvention.

Referring to Fig. 1, reference numeral it indicates a housing forsupporting a transparent enclosing block or panel, indicated generallyat H, which is illuminated by One or more suitable surfaces of lightwithin the housing, as will be more fully described hereinafter.

The housing comprises a front wall l2, side walls is, a top wall 14, aback wall l5, and a bottom wall it, the latter extending forwardly atll, of the front Wall G2, to prevent forward tilting of the sign.

The panel II has rearwardly turned portions l8 and it at the top andbottom respectively, said portions extending through openings providedtherefor in the front wall l2. It is to be understood, of course, thatthe panel or block H is of transparent material such as, for example, aclear plastic, or at least is substantially transparent.

Means for securing the free ends of the flanges or parts is and I9within the housing comprise brackets 28 and El located above and belowthe upper extension l8, and brackets 22 and 23 disposed above and belowthe lower extension [9. These brackets extend longitudinally of thehousing and are secured to the interior thereof by any suitable meanssuch as welding, soldering, or the like.

As shown in Fig. 2, there is a source of light for each of theextensions, there being a source of light 24 aligned with the upperextension, and a second source of light 25 aligned with the lowerextension. These sources of light may be of any suitable character,although they are shown as fluorescent tubes, which extendlongitudinally of the housing behind the respective extensions I8 and[9. These light sources are usually white but can be of any otherdesired color, or one may be of one color and the other of a differentcolor. If desired, in order to intensify the light reflected into thepanel I i, reflectors 26 and 27 may be provided about the tubes 24 and25 in such a manmay as to reflect the light from said tubes into theadjacent tubes of extensions 18 and id. The reflectors may be of ansuitable type, and are secured within the housing by any suitable means,not shown.

The light enters the respective extensions through the surfaces 28 and29 respectively, and is deflected from the curved longitudinal edges 3!and 3| respectively, so as to direct said light throughout the panel.edges 36 and 3| are such as to internally reflect the light and notallow it to escape, and the illuinination within the panel I! is theresult of the total internal reflection of light from said sources.

The rear surface of the panel may be treated in a variety of ways, butin Figs. 1 and 2 said surface is polished-and buifed. Likewise, the face32 of the panel is buffed and polished to a high degree so that it Willbe as invisible as possible, will internally reflect the light, and willpass the light reflected from the sign characters. When the Sign is seenin complete darkness, the face of the panel is completely invisible.However, when the The radii of the curved ters, numerals, emblems,sculpture, objects dart, decorative figures, facsimile objects, actualobjects, and all other usages where the principles enumerated hereinfind application. The purpose of the above Wording is to emphasize thefact that the essence of this inventionlight reflecting, transmittingand absorbing materials embedded within a substantially transparentpanel and illuminated-is applicable in many different fields.

As shown in Figs. 1 and 2, certain of the sign characters, indicatedgenerally at 35, and comprising the letters 0R0 extend in relief fromthe rear surface of the enclosing panel H in the direction of the face32, that is, the rear surfaces of these characters share a common planewith the rear surface of said panel. These letters possess opticalproperties different from the optical properties of the panel, and suchproperties may relate to color, degree of transparency, and/0'1-refractive index, so that they will be distinguishable when the deviceis illuminated. Embedded completely Within the panel are additional signcharacters, indicated generally at 36 and comprising the words Forquality. These words are located in front of the letters 0R0. The wordsFor quality are set off from the characters behind them and also fromthe rear surface of the enclosing panel so that they appear to besuspended in space. Thus the illusion of spaoiousness Within the panelis heightened. The words For quality can, if desired, be moretransparent than the letters 0R0 so that the latter may be seen in theirentirety simultaneous= 1y with the former.

It is to be understood that the sign characters 36 possess opticalproperties which are of such character as to make them readilydistinguishable in connection with the optical properties of the panel(which is essential to the invention) and the characters 35 (which isdesirable though not necessary).

Embedded within the panel is also a base for the characters 0R0, saidbase being indicated generally at 3'1. This base has no structuralpurpose in the sign because in fact all sign characters are held firmlyin place by virtue of being embedded in the panel. Rather its functionin this sign is decorative in seeming to support the letters CR0 andproviding a front face 36 which has the words Why not try the best?inscribed thereon, as indicated at 38. That is,

' the base is non-functional from the structural sign is seen insemi-darkness or in light. the face reflects a certain amount ofexternal light. However, these reflections can be substantiallyeliminated by the application of one of the glare and reflection-killingmicro-films of known character.

It is to be understood that the term sign characters as used herein, isintended to mean letpoint of view, but has an aesthetic function. Thebase 3? should be extremely transparent so as to permit the maximumpassage of light therethrough from the lower source of light 25. This isdesirable in View of the fact that the base 31 is located adjacent thelower end of the panel H and in the path of light passing through theextension iii and into said panel.

The characters 33 are on the front surface of the base 3'! and, incontrast to the other sign characters above described, the effect istwo-dimensional rather than three-dimensional, They may be applied inthe manner commonly used in the coloring of indicia or instrument dials.The differences between these sign characters and those found inordinary dials is that the former are completely embedded and insulatedfrom the air, whereas the latter are not.

In the present arrangement the sign characters Why not try the best? areilluminated mainly by conventional transmitted light and only partiallyby edge lighting. This is due to the fact that the source of'lightenters the panel directly behind these letters and they are seen 1against said source of light. This type of illumination gives adistinctly different appearance to the sign characters than where theyare edgelighted.

It is to be understood that in a sign of the present character theenclosing panel II should, in general, be more transparent than the mosttransparent sign character or figure within it, otherwise it would maskout some or all of said characters. Moreover, for the most strikingresults, sign characters superimposed in front of other charactersshould be more transparent than the latter.

Of course, the sign characters may be of various types and may havevarious characteristics. For example, there may be various optical char:acteristics which the materials may have for the purposes of thisinvention. These optical characteristics can :be listed as color, degreeof translucency, refractive index and an important fourth characteristicrepresenting combinations of the former three to form patterned,textured and mottled eifects. These latter in most cases result from themixing and incomplete fusion of materials of different colors, and/ordegrees of translucency, and/or indices of refraction. The materialswhich are used and the manner in which they are mixed determine theparticular pattern, or texture, in any given instance.

Regarding the material embedded within the enclosing block, severalcategories have been established. The first is best described asconstituting a thin interlayer, or what can be conceived as an embeddedsurface. This embedded surface is (1) disposed two-dimensionally (on aplane) within the panel, or (2) extends three-dimensi-onally within it.Whether disposed two-dimensionally or three-dimensionally within thepanel, it is always a thin interlayer of non-transparentalthoughpreferably near-transparent light reflecting material. In the secondcategory the material delineating the sign character extendsthree-dimensionally through the'mass of the sign character. thesedistinctions clear. If a transparent methacrylate letter is surface dyedand then embedded within a methacrylate block, there is a visibleinterlayer; this represents the first category. On the other hand, theletter may be formed from a sheet of methacrylate which, inmanufacturing has been caused to be dyed all the way through its mass;this represents the second category.

Taking the sign characters 35, the surfaces 4 may be colored and theyare then seen as an interlayer of color; or if they are colored all theway through their mass, they are seen by virtue of such coloring. Orthey may have their surfaces 40 slightly more opaque than the panel IIand are rendered visible by virtue of such degree of opacity. Further,these characters may be more opaque than the panel through their mass,and rendered distinguishable in this way.

A further alternative arrangement is'to' have the interlayer 40 of adifferent refractive index than that of the enclosing panel I I; or itmay be comprised of a material of a different refractive index than thatof the panel and extending three-dimensionally through the mass of saidcharacter. Or the same purpose (i. e., distinguishing the sign characterfrom the panel and rendering it visible) can be achieved by a mottledinterlayer at 40, or this same mottled effect can be translated into athree-dimensional form and Some examples will make '6 extend, throughthe mass of the sign character. It is, of course, to be understood thatthe coloring,.translucency and other characteristics above throughdifferences in color, translucency or refractive index, either singly orin combination.

For example, if the sign characters are red in color it is difficult forthe spectator to ascermixed together.

tain whether this coloring matter extends only over the surface of thecharacters or whether it extends through their massthis in spite of thefact that there exists an actual difference in effect between the oneand the other (i. e. a sign character colored through its mass absorbsmore light). Where mottled effectsare resorted to, however, the case isdifferent. Mottled effects,

it will be recalled, are the result of mixing materials of differentoptical characteristics in such a way that complete fusion does notresult. In

I this instance it is normally not diflicult for the spectator toascertain whether the mottled effect is an interlayer within the panelor extends through the mass of the sign character. The importance ofthese mottled eifects to the present invention justifies the emphasiswhich has been assigned to the differences between the aforementionedcategories. Three-dimensional textures and mottled patterns are amongthe most beautiful effects characteristic of this sign.

' Let us say, for, instance, that two transparent materials of differentindices of refraction are One might suppose, because both materials aretransparent, that they will remain invisible within the panel. However,this is not the case, at least when mixed in such a way that completefusion is not the result. In this instance discrete minute areas of onematerial are adjacent to the other. At the interface where the twomaterials conjoin a reflection' is established. Multiply these points ofrefiection by manythousands, insure there is a correct density of thesereflections per unit area, and the result is a flowing, apparentlyhomogeneous, mass of luminous material. When utilized this effectaccounts for the special luminosity of the sign characters in thepresent sign. Moreover, it represents the principal means whereby whiteand all color tints deriving from white are achieved.

It has been previously said that the sign characters, even thoughcolored, should preferably remain as transparent as possible. There areseveral reasons for this. For one thing, a sign character which is darkin color is correspondingly more opaque. In other words, the ratio oflight absorption to light reflection and transmission is weighted on theside of absorption, 1. e. the sign character is reduced in luminosity.Because light transmission and reflection are so preferred overabsorption dyes are normally, though not invariably, used in preferenceto pigments as coloring matter. Unfortunately, there is no such thing asa white dye. This explains theimportance of the special luminous effectdescribed in the previous paragraph.

,It .is not sufficient simply to create a threedimensional, mottledtexture using transparent eet-tan materials (if-different indices* ofrefraction-"tool:- "tain the aforesaid luminous effect '(which might bedescribed as a multiplied micro-point reflection'e'ffect), at least ifthe most intense lumi- -nosi'tyis to be had. Themat'erials chosen mustbe-right, not only asregards respective indices of refraction but alsoas regards the surface tension-establishedbetween 'the' two, The'number,"size and positioning of the 'niinute areasror "points within theenclosing vehicle must be correctly "calculated for maximum reflection.'For'examp'le, if the sign character is "too densily "pa cjiied with'these refiectmgpoints'oriareas most bf the 'lig'ht is'reflected fback"out before "it 'jpen'e- "tratesthe sign character; 1. e. it -is'ex'cessively opaque. *In"thisinstanc'e the sign ic'haracter is luminousaround "the "edges but "dull in the "middle portions. "Onthentherliand,'if "thereare not'a'sufficientnumber'nf these reflecting areas iscomparable to that of scatt'eredfstars against adark field. 'Thenagain,the 'smallerth'e points 'or areas of reflection the more conducive to "aWhat has been said 'in "preceding paragraph pertaining to the "word"O'R'O" also applies to 'thewords For quality, it being understood thatin determiningthe i-specific treatment of these "sets of "signcharactersthe two at leastdiffer "optically" in some respected as toafford contrast and variety. For example, the words "For quality "may bevery transparent so that "the word ORO'can 'be'seen throughthem"allowing an letters to he seensimultaneously. It i might .be suggestedthat only the surfaces be colored. in contrast to coloring through theirmass because the latter arrangement tends to "absorb more-light. Thus,'thesi'gn characters comprising the words For quality may "be"unsaturated in color (very little color, i.'e. a li'ghtsh'ade) andtherefore would be very transparent (as "opposed "'to' translucent oropaque) and of the "samere- "fractive index 'as that of theenclosing'panel "ll so there would'be no "glare or reflections lto cutdown transparency. .In contrast, the word 0R0 *may be deeper'in color,luminous owing to the micro-point reflection 'e'fie'ct .described in'the previous paragraph (perhaps combined with 'a three-dimensionaltexture) relatively jtransluc'ent,;and comprised lof'materials ofdifferent refractive indices than that of the panetl 1,

One of the 'sub 'c'ategories previously .de-

scribedan'emb'edded interlayer disposed on a plane'applies to'th'e signcharacters Why not try the best?"because these are two-dimensional "inevery sense. However, like the'threeediinensional sign characters thesetwo-dimensidnalletters can be saturated or unsaturated in respect tocolor; transparent, translucent or .opaquefiof the same or differentindices of refraction'from the panel I I or they may be mottled in theaforesaid. manner.

.By removing the sign characters or decorative figures from contact withthe air and embedding them within a substantially transparent block thebasic means is provided to control and exploit differences in color,translucency :and .re- .fractiveindex for thepurp'ose' of developing anindefiniterepertory of optical effects. The sadvantages of 'embedding'can lee-summarized as 1) "resulting in-azhighdegreeof controlotthebptical efiects desired, particularly as regards ithose effects(reflections and their absence) resulting ifrom' -the combination-ofmaterials of dissimilar J .-.sure":thatzthe colorcis notso darkcthat. itabsorbs too :much-ofthe illumination or masks out the sign characters.If it is desired that the sign ets-*wllas identical'indicesofrefraction, 2) ;an "economicalutilization or the light en'tering theblock from the edge resulting from'the propertyoftotalinternalreflection, (3) a more even illumination-of the 'signcharacters also owing to the effects of the total internal reflection oflight, (4) .a'more .even illumination of the sign characters'owing tothe control which is exerfcised over the indices of refraction of theembedded sign characters and the panel, (5) the desirable eifect on theappearance of the "sign characters when seen through the refractory,

"transparent medium, (6) providing a transparent, invisiblesuperstructure, or support, .for the sigircharacters holding them in aproper position'relative to the source of illumination and to ,theother'elcm'ents constituting the over-all -Sign-.a subject which has notpreviously been mentioned. To .an uninformedobserver it would appearthat the sign characters are manufactured apart from the. enclosingpanel and only subsequently embedded within. it. But as ainatter of facttheprocedure may involve molding the enclosing .panel .first with the:sign char- .acters (or moreprecisely, the shapes of the signcharacters) already apart ,of-the panel as deep recessesin its-rearsurface. Then, with-a subsequent molding operation, the recesses arefilled .in solid tozproduce-the result seen by 'theobserver. When this,method is followed the panel is rightly conceivedasa necessaryantecedent to the manufacture of the sign characters themselves.vl-nzeiiect the panel itself is a illOldf-ih which-the lightrefiectingmaterials comprising the signcharacters arev formed.

.While the transparent panel could; if desired, be made of almost anytransparent material,

eplastiesgsuch as epolystyrene and methacrylate havebeen. found highlydesirable. .Where'ther- -Without going 'into detail turing the sign,some discussion of thesubject 'Will-serve'to clarify-certain features ofthe'sign itself.

For eXam-ple,= if it::is intended that thevenclosingwpanelabeslightlycoloredplet us say'tinted .throughoutrits mass, molding powde'risselected of "the :proper: color; care being exercised 'to incharactersare'seen byvirtue of a light reflect- "The: panel is then inserted in amold and sameztoharacteristics as those of the panel itself.

-A's an alternative the recesses can be left uncoated-and"fille'd'inwith a colored plastic; or as =a' fu'rther 'alternative the two methodscan be "combined.

Let us say, on the-other hand, that the sign cliaracters are to berendered visibleby virtue of a three-dimensional interlayer which ismottled. In this case the recesses are sprayed with a special mixtureconsisting of two or more light reflecting insoluble, incompatiblematerials. The failure of these materials completely to merge results inpatterns and. mottled effects which are very effective, especially whenseen under the conditions of edge lighting. By combining materials ofdiiferent chemical composition, colors, degrees of translucency, andrefractive indices a great variety of effects can be secured.

Or let us say that the recesses are sprayed with a special mixtureconsisting of minutely granulated transparent particles of a givenrefractive index immersed in a vehicle of a different refractive indexavehicle, moreover, in which they are insoluble. Being insoluble in saidvehi cle the surface irregularities of these minute granules arepreserved and being immersed in a surrounding medium of a differentindex of refraction they are light reflecting. The recesses being filledin with a material of optical characteristics identical with those ofthe panel, and thepanel being edge lighted, the sign characters are,rendered visibleby virtue of this encased frosted effect (which, be itsaid in passing, is in effect the interlayer counterpart of themicropoint reflection effect). Somewhat the same result may beobtainedby roughening the recesses with sand blasting apparatus, coatingthem with a material of adiiferent refractive index from that of thepanel and in which the material comprising the panel is insoluble, andfilling in the recesses are previously described. The above are methodsof achieving whiteness and,luminos-,

ity inthe sign characters and in this respect have the same function asthe micro-point reflection fie t- Where it is desired. that a mottledeffect extend three-dimensionally through the mass of the sign charactera different procedure is followed. In this instance the recesses in therear surface of the panel are left uncoated and a plastic compound withwhich the recesses are filled isof a special character. In other words,the mixture which is fed into the hopper of the injection moldingmachine consists of at least two different materials, or if the mixtureconsists of the same plastic material there must at least be adifference as regards color and/or degree of translucency. For instance,a given mixture might consist of three constituents, all of them thesame methacrylate plastic: (1) 50% transparent powder, (2) 30% coloredpowder and (3) 30% a powder which is somewhat more opaque than both ofthe preceding. Whenthe granules are'heated in the heating cylinder ofthe molding machine they soften and by action of a ram are forced intothe mold cavity and finally into the recesses in the rear surface of thepanel. Complete mixture of the three constituent materials does notoccur, however, because they never become sufiiciently liquid to fuse.Rather, the result is a three-dimensional mottled effect comprised oftransparent, translucent and colored areas. By varying the compositionof the mixture as regards the type, size, proportion and number of theconstituent granules an infinite number of effects can be obtained.

The micro-point reflection effect, as regards technique ofmanufactureand in other respects as well, is' related to the immediately preceding.What is required in this instance, however, is a mixture of at least twosubstantially transparent materials'of different indices of refraction.It

will be recalled that the micro-point reflection effect results whereminute areas, or points, of a given index of refraction are surroundedby a vehicle of a different refractive index and are illuminated. Whilea certain amount of luminosity will always result from this combinationmaximum reflection is contingent upon (1) the nature of the materialscomprising respectively the embedded minute areas and the surroundingvehicle, (2) the respective indices of refraction of the embedded areasand the vehicle, (3) the size of the embedded areas, (4) their position,and (5) their density relative to the surrounding vehicle. Control ofthese in the molding operation is obtained by a correct determination of(1) the types of materials making up the mixture, (2) the proportion, orratio, by weight of these constituent materials, (3) the size of thegranules of the respective constituent materials, and (4) generalmolding conditions.

For example, as regards the types of materials used, one might be atransparent, thermoplastic material of a given index of refraction andthe other a transparent thermosetting. plastic of another index ofrefraction, keeping in mind that the granules of thermosetting materialare to comprise the minute, light reflecting areas within the vehiclewhich is made up of the thermoplastic material. Because thethermosetting granules do not soften under the effect of heat theymaintain their identity and shape during the injec-v tion operation.This introduces an added element of control into the molding operationacontrol which is apt to'be materially lessenedv when two thermoplasticmaterials are used. Then again, because a correct density of thereflecting points, or areas, within the vehicle is necessary if maximumreflection is to result, the

, proportion, or ratio, in which the respective sets 7 however, at theinterface between a gas and a of granules are mixed is of utmostimportance.

Importance must also be attached to the absolute and relative sizes ofthe granules comprising the mixture. It will be recalled that themicro-point reflection effect is most efiective where the reflectingsurfaces are extremely minute and contribute to an effect of a glowingsuch as neon gas. These reflecting surfaces can be no smaller than thegranules of which they are comprised.

In the preceding the micro-point reflection effect is described asresulting from the comolding of two or more tpyes of. granulated plasticmaterials. When this method is followed any given reflection resultsfrom the conjoining of two solid materials of. different refractiveindices,

said reflection taking place at the interface between these materials.Reflection can alsoresult,

solid, let us say, for example, where air and a plastic materialconjoin. This can be achieved by heating transparent plastic granules ofhomogeneous composition in a mold and compressing them, insuring thatthe pressure is not so excessive that all the air is driven out. Inother words, if the exact amount of heat and pressure areapplied minutepockets of air remain trapped within the sign character. Reflections areestablished where the air pockets and surrounding plastic vehicleconjoin. The effect-is substantially the same as that previouslydescribed. While it is possible to exercise this pressure control wherecompression molding technique is utilized, it is less feasible wheninjection or. transfer molding operations are used. The desired effectmay also be secured by having reflecting areas consist of minute pocketsof a liquid mate rial. embedded. within a. solid vehicle, or. even that.the reflecting. areas: might consist. of discrete solids immersed in aliquid, or solids immersed'ina gas. An example ofv the latter. migi: be.something onthe order. of spun glassstuiied or blown into the recesses.of the transparent panel g It. was previously said that embedding thesign. character within the enclosing panel permitscontrol of therefractive index. of the. sign character relatire to that of the panel,Theserefractive indices may or. may not bethe same. If, they areidentical. no. glare. effects emanate at. the interface between. thesign character and. the enclosing panel. Qn the other. hand,.if there.-- fractive. indices. vary the. contrary holdstrue.

Whenithetwo. refractiveindices are diiferentiandl resulting1are.effects,-. these latter are not. uni..- formly distributed overthe entire. surface or" the sign character; rather they are. localizedatcertainpoints. Thisis. held to be a limitation characteristic of. manyplastic. illuminated signs now in usea limitation which resultsfrom thefact that the. light does. not approach every part of the surface of thesign character with the. same 2:.

angle of' incidence. In these. cases, any particiu lar pattern. oflight. reflection is. determinedby the conformation. of the interface.(1. e. th.5p:= ciflc shape of the signcharacter) relative to the. angle.of; incidence of the illumination. In so far as. the manufacturer ofthesign character. determines its. Shape it. indirectly determines.v the.pat-.- ternofli'ght reflections which result. In.v actual practice,however, the latter is largely an un foreseen result and essentially.accidental.

Taking, for instance, the letter R in the. word. R0: if this letter is,comprised of a material of a different refractive index from that of thepanel certain parts of its. surface will be subject to glare and willthus. be rendered visible; the. remaining, parts. however,. will remain,invisible. when the sign character and panel are of different indices ofrefraction, total internal reflection takes place within the signcharacter as well as within the enclosing. panel; In other words,.theinterface between the sign character and'thepanelexerts the sameactionon theimpinging. light 'asthe interface between the panel and. thesurrounding air. Assuming. theTrned-i'um in which-the. sign character isimmersedisof a different refractive index than that of the signcharacter it is more or less irrelevant, considered from: the standpointof appearance, whether this.

medium be a solid, such as the plastic of the enclosing panel, or a gas,such as the atmosphere. This is. assuming, of course, that illuminationin both instances is by total internal reflecti cn.

When a sign character is comprised of the micro-point reflection eifectextending substantially. through its mass. itis again-more or lessirrelevant, from the. standpoint of appearance. Whether said signcharacter is immersed? in a solid or gaseous medium. Assuming, at least,that the mediumis of adifferent refractive indexthan. the predominantmaterial of thesign. character, with the resultinglocalizedlglareeffects, the latter are overwhelmed. by the. prevails inghigh luminosity of the letter as. a whole. In other words, thereflections at the interface con joining. the sign character. and. the.panel are invisible and thus neither augment nor lessen the. cleardefinition of. the sign character. Considered from this point of view asign character comprised of the micro-point reflection effect, or

This is. owing to the fact that,

. embody. the micro-point reflection efiect.

sign characters comprising the micro-point rcflection effect, and itsvariations, are considered within the scope of this invention even whendisassociated from. the enclosing panel as shown. in. Fig. 5. In. thisfigurereference numeral 58. indicates the housingcontaining theillumination unit. Abase 5|, for. the sign. characters or letters. 0R0indicated generally at 52,. is shown disposed. on. the housing, saidsign characters 030 being shown mounted on the base M which, if.desired. may be. so. constructed as to The words.l?or quality may beprovided'cn the front. face of. the. base 5i in the mamier described inconnection with the. words Why not. try, the best? on thebase 31 in Fig.2.

Unlike other optical effects characteristic of and. important to the.present invention, the. micro-point eifect does not depend on theenclosing panelfor its success.-

While the panel is typically transparent it,. too, may be treated invarious Ways as regards color, translucency and'mottl'ed effects. Forin.- stance. the enclosing panel. can. often be made. more attractive bybeing. tinted with color,. either over its surface or through its mass.This. can. be done if. the degree of color saturation. is not. soexcessive. as. to cancel out too large aportionof. the light. emitting.from: the. interior thereof; Moreover, it should be remembered thatthesum. total-effectshouldbe no more. opaque than. the. mosttransparent. portion. of. the. material. em? bedded Within the blockwhich. is. meant; to. be seen -by the observer. Thenagain, the.enclosing-. panel can be mottled, for instance, three-dimemsionallytextured through its. mass. Needless to say, the caution.exercised in. respect. to. color. is exercised in. respect to. thesemottled. effects as well.

A variation or alternative arrangement ofthe. invention pertains to the.use: of luminescent (fluorescent andphosphorescent). dyes. and pigmentsas a substitute for the normal. coloring matten. For these purposes. theillumination source shouldbe. rich. in ultra-violet energy and filters61 used. These filters. are. mounted in" grooves provided therefore invthe. respective brackets-22,. 2-3 which are of such character as toabsorb the visible light and pass the ultravioletlighti There existsthe" further possibility of a sign which combines the'feature ofavisible, aswell as: a luminescent sign. This-can/be done by usingcoloring matter whichis suitable for illumination by visible light, butwhich also possesses luminescent properties. Needless to say, theappearance of the sign under the two different sources of. illuminationis-markedly diiferent. It is. also 'to be understood that the filter M-may beused to determine the character and color of. visible light and ifdesired one 'filter'may be used toprov-ide one color and the. other usedto the other letters; the letters are incompletely seen and the visionis confused. This is not the case with the present sign. When the.person viewing the letters moves from a position directly in front ofsuch sign, refraction causes the letters apparently to shorten, but thewhole of any letter can still be seen (within reasonable limits). Thus,the sign characters are seen in their en.- tirety as clearly from theside as from the front. Combined are the depth and substantiality of athick letter seen from the front and the legibility of a shallow letterseen from the side. This special characteristic results from embeddingthe block letters in a refracting medium.

An additional feature of the invention is the provision for theembedding of a real object, or a facsimile object, as shown in Fig. 4wherein said object comprises a bottle 42, although other objects may beused, depending upon what is being advertised; and, of course, writtenor other material may be used in connection with such object.

Moreover, the shape of the panel can be made surface and then forcingthis pattern on to it using the original grained material itself or ametal die. Or, the rear surface can be silvered so as to function like amirror. In this way the thickness of the sign characters ORO can beapparently doubled owing to the reflection set up.

I claim:

1. An illuminated sign comprising:' a one-piece solid molded panel oflight transmitting material, said panel having a cavity therein in whicha sign character comprising a solid substance of optical characteristicsdifferent from said panel is molded so as to be fully embedded withinsaid p a nel and united thereto by molding whereby no interlayer of airexists between the contacting surfaces of said sign character and saidpanel,

none of the surfaces of said sign character being coplanar with anysurface of said panel thereby creating the appearance of beingunattached to to conform to the general shape of said bottle or otherobject. 1

Another possible variation provides for the bottle or other objectpartly enclosed and partly outside of the panel ll, interpenetrating itas it were, and even further variations are possible.

In summary, the characteristics of the enclosing block or panel ll neednot exactly conform to those shown in the drawing. In general, however,it can be said that its face should be highly polished and that itshould be of such a shape as to reflect the light internally with a highdegree of efficiency directing the rays to the sign characters. Forspecific effects the face of the enclosing panel can be given a contourwhich, owing to the effects of optical refraction, results in an opticaldistortion of the sign characters within the block. For certainapplications, i. e. decorative figures such as flowers, etc. the shapeof the enclosing block may be cylindrical. Here again, however, itshould be noted that the nonplanar shape of such a surface gives rise topronounced refractory elfects. Such effects, however, can be highlyillusory and intriguing. The panel, while normally transparent, can, ashas been pointed out above, be treated in various ways, i. e. it can bethree-dimensionally textured, colored, etc.

While the panel H may have its rear surface highly polished, and thusinvisible to the observer, another method of treating said surface isshown in Fig. 3 wherein an appropriate material such as paper or cloth,on which is printed or otherwise reproduced a texture, design orpattern, is impregnated with a-transparent plastic material and underheat and pressure the material is forced against the rear surface of theenclosing panel so as to become physically and optically united to it,as indicated at 63. The light rays traveling through the panel arereflected from this layer to the observer and enable the design to beseen. An advantage of this method is that the effect of almost anymaterial or texture-cloth, metal, wood, etc.can be reproduced. Theprocess involved is one of lamination.

It is also to be noted that an actual material, such as a monks cloth ora velvet, can be impregnated and then laminated to the rear surface ofthe enclosing block.

' A grain duplicating that of coarse wood or other appropriate materialcan be given to the rear surface by heating and softening the rear anysurface of said panel and of being freely suspended therein, and meansfor illuminating said sign.

2. An illuminated sign comprising: a onepiece molded panel of lighttransmitting material, said panel having two cavities therein in whichsign characters comprising solid substances of optical characteristicsdifferent from said panel are molded so as to be embedded within saidpanel and united thereto by molding whereby no interlayer of air existsbetween the contacting surfaces of said sign characters and said panel,one sign character having its rear surface coplanar with the rearsurface of said panel and being substantially opaque relative to theother sign character, and the other sign character having none of itssurfaces coplanar with any surface of said panel and positionedsubstantially in front of the first sign character thereby creating theappearance of being unattached to any surface of said panel and of beingfreely suspended therein, the sign character in front beingsubstantially transparent and allowing the sign character in the rear tobe seen simultaneously with it, and means for illuminating said sign.

3. An illuminated sign comprising: a onepiece solid molded panel oflight transmitting material, said panel having a cavity therein in whicha sign character of optical characteristics different from said panel ismolded so as to be fully embedded within said panel and united theretoby molding whereby no interlayer of air exists between the contactingsurfaces of said sign character and said panel, said sign charactercomprising a vehicle of transparent material in which are embeddedminute particles of a transparent material of a different index ofrefraction from that of said vehicle, the size, number and distributionof said particles in said vehicle producing a reflection effect of greatdepth and intensity, none of the surfaces of said sign character beingcoplanar with any surface of said panel thereby creating the appearanceof being unattached to any surface of said panel and of being freelysuspended therein, and means for illuminatin said sign.

4. An illuminated sign comprising: a onepiece solid molded panel oflight transmitting material, said panel having a cavity therein in whicha sign character of optical characteristics different from said panel ismolded so as to be fully embedded within said panel and united theretoby molding whereby no interlayer of air exists between the contactingsurfaces of said sign character and said panel, said sign charactercomprising a vehicle of transparent material in which are located minutecavities of a gaseous transparent material of a different index ofrefraction from that of said vehicle, the size, numher and distributionof said cavities in said vehicle producing a reflection effect of greatdepth and intensity, none of the surfaces of said sign character beingcoplanar with any surface of said panel thereby creating the appearanceof being unattached to any surface of said panel and of being freelysuspended therein, and means for illuminating said sign.

ROBERT W. MALLARY.

REFERENCES CITED UNITED STATES PATENTS Name Date Holfert Jan. 31, 1893Number Number Number Great Britain July 19, 1940

